1. Field of the Invention
The present invention relates to a method for molding various kinds of synthetic resin moldings. In particular, the present invention relates to a method for molding thermoplastic elastomer resin moldings preferably used as medical containers such as infusion containers, blood collecting tubes, and the like, or as plug bodies to which a needle can be stuck in medical caps.
2. Description of the Prior Art
Conventionally, as a method for molding using synthetic resin raw materials, compression molding methods by which resin raw materials which were put in a mold are pressurized and molded has been proposed as disclosed in Japanese Patent Laid-Open Publication No. 2003-275278.
However, unlike generally used injection moldings, in the above mentioned compression moldings, a block of a resin raw material is pressurized and molded in a mold, and therefore, metering and injection are not conducted at the same time, while pressurizing is applied while filling in the mold as injection moldings. Therefore, in compression moldings, a resin cannot be replenished during the molding process and contents or shapes change in said mold. Therefore, when the amount of resin raw materials to be put in a mold is too much, burr is likely to occur, while on the other hand, when the amount of resin raw materials to be put in a mold is too little, prescribed moldings cannot be obtained and become defective. Therefore, to establish a method for putting raw materials in a mold made up of a bottom force and a top force, and to set conditions for putting raw materials in a mold are the important issues to be solved in a compression molding method. In particular, in the case of a plug body for infusion in which sticking operations are conducted using injection needles and the like, unlike thin moldings such as packings obtained by compression moldings such as mere press moldings, single resin moldings must be obtained which have thickness and uniform quality as a whole since it is necessary that said moldings are provided in an opening portion of an infusion container which is set upside down at the time of use and that liquid leakage of infusion in a container must be prevented in keeping the state of the infusion container being upside down.
In this regard, such kinds of conventional molding methods do not necessarily disclose satisfactory technology regarding methods for feeding raw materials in molds and feeding condition, and in particular, there has been no disclosure as to the methods for molding thick molds having uniform quality as a whole by compression molding methods.
Therefore, the object of the present invention is to solve the above mentioned problems and the object of the present invention lies in providing a method for molding synthetic resin moldings capable of continuously obtaining thick synthetic resin moldings having uniform quality as a whole.